Washing machine and control method thereof

ABSTRACT

A washing machine that can determine a weight of laundry in consideration of the result of determination on whether the laundry is dry cloth or wet cloth, and a control method of the washing machine. Before washing starts, a drum rotates to measure a changed amount in water level, and it is determined whether laundry is dry cloth or wet cloth based on the changed amount in water level. If it is determined that the laundry is wet cloth, a weight of the laundry is accurately detected by using wet cloth weight criteria or by adding a weight according to the changed amount in water level, which leads to reducing water consumption, a washing time, and energy consumption while preventing laundry from being damaged.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.10-2013-0127648, filed on Oct. 25, 2013 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

BACKGROUND

1. Field

Embodiments of the present disclosure relate to a washing machine ofdetermining a weight of laundry in consideration of the result ofdetermination on whether the laundry is dry cloth or wet cloth, and acontrol method of the washing machine.

2. Description of the Related Art

In general, a washing machine (e.g., a full automatic washing machine)includes a tub to load water (washing water or rinsing water), a drumrotatably installed inside the tub to accommodate laundry, a pulsatorrotatably installed inside the drum to generate streams of water, and amotor to generate a driving force for rotating the drum and thepulsator. The washing machine removes contaminants from laundry throughsurface action between streams of water and detergents.

The washing machine washes laundry through a series of operations: awashing process of removing contaminants from the laundry with water (indetail, washing water) in which detergents have been dissolved; arinsing process of rinsing the laundry with water (rinse water)including no detergents to remove remaining bubbles or detergents fromthe laundry; and a dehydrating process of removing water from thelaundry by centrifugal force.

When washing is done through the series of operations described above,the motor is driven at predetermined Revolution Per Minute (RPM) and apredetermined driving rate during each of the washing process, therinsing process, and the dehydrating process. The RPM and driving rateof the motor for each process is set depending on the weight (load) ofthe laundry.

Accordingly, there is a need for accurately determining a weight oflaundry in order to control driving of a motor according to the load ofthe laundry and to determine an amount of water and a time that areconsumed for washing and rinsing processes.

Conventional washing machines determine a weight of laundry beforestarting washing. The weight of laundry is determined by calculating anacceleration time taken for the velocity of a drum in which the laundryis loaded to reach a predetermined velocity when applying predeterminedtorque (or, a predetermined voltage) after accelerating the velocity ofthe drum to a predetermined velocity.

However, when the laundry is wet cloth, the weight of the laundry may bewrongly determined as a load more than the actual amount of the laundry.In this case, a greater amount of water, a longer time, and higherenergy will be used for washing and rising processes than those requiredfor the actual amount of the laundry, which may lead to damaging thelaundry and wasting water.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide awashing machine that accurately determines a weight of laundry bydetermining whether the laundry is wet cloth or dry cloth and applyingdifferent weight criterion according to the result of the determination,and a control method of the washing machine.

Additional aspects of the disclosure will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

In accordance with one aspect of the present disclosure, a controlmethod of a washing machine, the washing machine including a tub toaccommodate water therein, and a drum rotatably installed in the tub andconfigured to accommodate laundry therein, the control method includes:determining whether the washing machine starts operating; rotating, ifit is determined that the washing machine starts operating, the drumbefore supplying water to the tub; measuring a changed amount in waterlevel according to the rotation of the drum to determine whether thelaundry is dry cloth or wet cloth; and setting, if it is determined thatthe laundry is wet cloth, a washing condition corresponding to wetcloth.

The control method may further include a washing motor configured torotate the drum, wherein the rotating of the drum includes rotating thewashing motor at Revolution Per Minute (RPM) for dehydrating watercontained in the laundry.

The RPM may be equal to or more than 90 RPM.

The control method may further include a water level sensor configuredto measure a level of water loaded in the tub, wherein the determiningof whether the laundry is dry cloth or wet cloth includes: measuring alevel of water loaded in the tub using the water level sensor beforerotating the drum; measuring a level of water loaded in the tub usingthe water level sensor after rotating the drum; and measuring a changedamount in water level by comparing the level of water measured beforerotating the drum to the level of water measured after rotating the drumto determine whether the laundry is dry cloth or wet cloth.

The control method may further include determining, if a changed amountin water level is measured, that the laundry is wet cloth.

The control method may further include determining, if no changed amountin water level is measured, that the laundry is dry cloth.

The setting of the washing condition corresponding to wet cloth mayinclude determining a weight of the laundry using weight criteria thatis different from weight criteria to be used when the laundry is drycloth.

The control method may further include a washing motor configured torotate the drum, wherein the determining of the weight of the laundrymay include estimating a weight of the laundry using an accelerationtime taken for the drum to reach a predetermined velocity whenpredetermined torque is applied to the washing motor.

The determining of the weight of the laundry may include performing, ifit is determined that the laundry is wet cloth, a wetting process to wetthe laundry, and then estimating a weight of the laundry.

The determining of whether the laundry is dry cloth or wet cloth may beperformed before a water supply process of initially supplying water inorder to wash the laundry.

The determining of whether the laundry is dry cloth or wet cloth may beperformed before determining the weight of the laundry.

In accordance with another aspect of the present disclosure, a washingmachine includes: a tub configured to accommodate water therein; a drumrotatably installed in the tub and configured to accommodate laundrytherein; a washing motor configured to rotate the drum; and a controllerconfigured to control the washing motor to rotate the drum beforesupplying water to the tub, to measure a changed amount in water levelaccording to the rotation of the drum, and to set a washing conditionaccording to the changed amount in water level.

The controller may rotate the drum at Revolution Per Minute (RPM) fordehydrating water contained in the laundry.

The washing machine may further include a water level sensor configuredto measure a level of water loaded in the tub, wherein the controllermay measure a level of water loaded in the tub using the water levelsensor before rotating the drum, measure a level of water loaded in thetub using the water level sensor after rotating the drum, and measure achanged amount in water level by comparing the level of water measuredbefore rotating the drum to the level of water measured after rotatingthe drum to determine whether the laundry is dry cloth or wet cloth.

If a changed amount in water level is measured, the controller maydetermine that the laundry is wet cloth.

The controller may determine a weight of the laundry using anacceleration time taken for the washing motor to reach a predeterminedvelocity when predetermined torque is applied to the washing motor.

If it is determined that the laundry is wet cloth, the controller mayperform a wetting process to wet the laundry before determining a weightof the laundry.

The controller may determine whether the laundry is dry cloth or wetcloth according to the changed amount in water level, and determine aweight of the laundry using different weight criterion depending onwhether the laundry is dry cloth or wet cloth.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the disclosure will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a cross-sectional view illustrating a configuration of awashing machine according to an embodiment of the present disclosure;

FIG. 2 is a block diagram illustrating a control configuration of awashing machine according to an embodiment of the present disclosure;

FIG. 3 is a flowchart illustrating a control method of a washingmachine, according to an embodiment of the present disclosure; and

FIG. 4 is a cross-sectional view illustrating a configuration of awashing machine according to another embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

FIG. 1 is a cross-sectional view illustrating a configuration of awashing machine according to an embodiment of the present disclosure.

Referring to FIG. 1, a washing machine 1 may include a cabinet 10 havinga box shape and constituting an external appearance of the washingmachine 1, a tub 11 installed inside the cabinet 10 and configured toload water (washing water or rinsing water) therein, a drum 12 rotatablyinstalled inside the tub 11 and configured to load laundry therein, apulsator 13 rotatably installed inside the drum 12 and configured torotate in a left or right direction (forwardly or backwardly) togenerate streams of water, and a washing shaft 17 which is perpendicularto the ground.

The drum 12 has a cylindrical shape wherein the top part opens, and aplurality of through-holes 12 a are formed around the drum 12. Abalancer 12 b may be provided in the upper part of the drum 12 so thatthe drum 12 can stably rotate upon high-speed rotation.

Below the tub 11, a washing motor 14 to generate a driving force forrotating the drum 12 and the pulsator 13, and a power switching device15 to transfer the driving force generated by the washing motor 14 toboth or one of the drum 12 and the pulsator 13 may be provided.

The drum 12 may be connected to a hollow dehydrating shaft 16, and thewashing shaft 17 installed in the cavity of the dehydrating shaft 16 maybe connected to the pulsator 13 through a washing shaft connectingelement 18.

The washing motor 14 may be a Direct Drive (DD) type motor having avariable speed function. The washing motor 14 may transfer a drivingforce to the drum 12 or the pulsator 13 according to an upward/downwardmovement of the power switching device 15.

The washing motor 14 may be a universal motor composed of a field coiland an armature, or a Brush Less Direct Current (BLDC) motor composed ofa stator and a rotor. However, the washing motor 14 may be any othermotor as long as it can be applied to the washing machine 1. Also, thewashing motor 14 may be a belt type.

The power switching device 15 may include an actuator 15 a to generate adriving force for switching power, a rod element 15 b to move linearlyaccording to an operation of the actuator 15 a, and a clutch element 15c connected to the rod element 15 b and configured to rotate accordingto a movement of the rod element 15 b.

The washing motor 14 may perform wetting cloth, dissolving detergents,washing, dipping and rising, and untangling cloth by rotating thewashing shaft 17 forward or backward when coupling between the washingshaft 17 and the dehydrating shaft 16 is released to thus move thepulsator 13 in left and right directions.

Also, the washing motor 14 may rotate the washing shaft 17 and thedehydrating shaft 16 in a forward or backward direction when the washingshaft 17 is coupled with the dehydrating shaft 16 so as to rotate boththe pulsator 13 and the drum 12 in the same direction, therebyperforming a shower-rinsing process and a dehydrating process.

A water level sensor 19 for detecting a frequency changing according toa level of water to determine an amount (level) of water loaded in thetub 11 may be installed on the lower inner surface of the tub 11.

A drain 20 to discharge water loaded in the tub 11 to the outside may beformed in the bottom of the tub 11, and the drain 20 may be connected toa first drainpipe 21. A drain motor 22 to control drainage may beinstalled in the first drainpipe 21, and an outlet of the drain motor 22may be connected to a second drainpipe 23 to discharge water to theoutside.

In the upper part of the cabinet 10, a door 25 for opening or closingthe washing machine 1 in order to put laundry into the drum 12 or totake laundry out of the drum 12 may be mounted.

In the upper part of the tub 11, an opening 27 to put laundry into thedrum 12 or to take laundry out of the drum 12 may be formed, and theopening 27 may be opened or closed by the door 25.

Also, a water-supply pipe 40 to supply water to the tub 11 may beinstalled in the upper part of the cabinet 10. One end of thewater-supply pipe 40 may be connected to an external water-supplysource, and the other end of the water-supply pipe 40 may be connectedto a detergent supply unit 41. Water supplied through the water-supplypipe 40 may be supplied to the tub 11 together with a detergent via thedetergent supply unit 41. The water-supply pipe 40 may include awater-supply valve 42 to control supply of water.

Meanwhile, the tub 11 may be supported by a suspension system 43 withrespect to the cabinet 10, and a checker switch 44 to detect shakingthat occurs when a user touches the drum 12 in order to take laundry outof the drum 12 may be installed between the tub 11 and the cabinet 10.In addition, when the drum 12 rotates eccentrically due to an unbalancedload of laundry, the checker switch 44 may detect excessive vibration ofthe tub 11 when the tub 11 hits the checker switch 44 before hitting thecabinet 10.

FIG. 2 is a block diagram illustrating a control configuration of awashing machine according to an embodiment of the present disclosure.Referring to FIG. 2, a washing machine 1 may include an input unit 50, acontroller 52, a memory 54, a driver 56, and a display unit 58.

The input unit 50 allows a user to input a command for performing awashing process, a rinsing process, and a dehydrating process of thewashing machine 1. The input unit 50 may be configured with keys,buttons, switches, and a touch pad, and may include all devices capableof generating predetermined input data through a manipulation, such aspressing, contacting, pressure, and rotating.

Also, the input unit 50 may include a plurality of buttons (a powerbutton, a reservation button, a button for setting temperature of washwater, a soak function button, a washing button, a dehydrating button, awater level selection button, etc.) allowing a user to input a commandrelated to an operation of the washing machine 1. The buttons mayinclude operation buttons 51 allowing the user to input a start commandor a pause command.

The controller 52 may be a micom for controlling overall operations ofthe washing machine 1, such as washing, rinsing, and dehydrating,according to driving information received from the input unit 50. Thecontroller 52 may set goal levels of water (a level of washing water anda level of rinsing water), goal RPMs, a motor driving rate (on and offtimes of the washing motor 14 (see FIG. 1)), a washing time, and arinsing time, according to a weight (a load) of laundry determined in awashing course.

Also, the controller 52 may determine whether laundry is dry cloth orwet cloth, before a weight (a load) of the laundry is determined afterthe laundry is put into the drum 12 (see FIG. 1). In order to determinewhether laundry is dry cloth or wet cloth, when laundry is put into thedrum 12, a current level of water loaded in the tub 11 may be measuredusing the water level sensor 19 before washing starts. Thereafter, thedrum 12 may rotate at first RPM (about 90 RPM to 250 RPM for dehydratingwater contained in the laundry) for a predetermined time period (about 1to 2 minutes) to dehydrate water contained in the laundry. Then, a levelof water may be again measured using the water level sensor 19.

If the laundry is dry cloth, since no water is discharged from thelaundry although the drum 12 rotates at the first RPM for thepredetermined time period, there will be no difference between the levelof water measured before the drum 12 rotates and the level of watermeasured after the drum 12 rotates.

However, if the laundry is wet cloth, since water contained in thelaundry is discharged when the drum 12 rotates at the first RPM for thepredetermined time period, there will be a difference between the levelof water measured before the drum 12 rotates and the level of watermeasured after the drum 12 rotates.

Accordingly, the controller 52 may compare the level of water measuredbefore the drum 12 rotates to the level of water measured after the drum12 rotates. If the controller 52 determines that there is no differencebetween the measured levels of water, the controller 52 determines thatthe laundry is dry cloth, and if the controller 52 determines that thereis a difference between the measured levels of water, the controller 52may determine that the laundry is wet cloth.

In other words, if the controller 52 determines that the level of watermeasured after the drum 12 rotates is higher than the level of watermeasured before the drum 12 rotates (that is, if the controller 52determines that water has been added), the controller 52 may determinethat the laundry loaded in the drum 12 is wet cloth.

Also, the controller 52 may apply different weight tables according tothe result of the determination on whether the laundry is dry cloth orwet cloth, so as to determine a weight of the laundry.

For example, when the controller 52 determines that the laundry is drycloth, the controller 52 may determine a weight of the laundry bycalculating an acceleration time taken for the velocity of the drum 12to reach a predetermined velocity when applying predetermined torque(or, a predetermined voltage) after accelerating the velocity of thedrum 12 to a predetermined velocity. Since the acceleration time isproportional to the weight of the laundry, the controller 52 mayestimate a weight of the laundry using a dry cloth weight tablecorresponding to the acceleration time.

Meanwhile, when the controller 52 determines that the laundry is wetcloth, the controller 52 may determine a weight of the laundry bycalculating an acceleration time taken for the velocity of the drum 12to reach a predetermined velocity when applying predetermined torque(or, a predetermined voltage) after accelerating the velocity of thedrum 12 to a predetermined velocity. Likewise, since the accelerationtime is proportional to the weight of the laundry, the controller 52 mayestimate a weight of the laundry using a wet cloth weight tablecorresponding to the acceleration time.

However, when the laundry is wet cloth, a level of water measured afterthe drum 12 rotates may depend on a wet degree of the laundry.Accordingly, it is difficult to accurately estimate a weight of wetcloth using one wet cloth weight table.

For example, a level of water measured after the drum 12 rotates variesaccording to various conditions of wet cloth, such as a case in whichlaundry is fully wet, a case in which laundry is damp although it is notfully wet, and a case in which a part of laundry is wet cloth and theremaining part of the laundry is dry cloth.

Accordingly, in order to accurately estimate a weight of laundryregardless of a wet condition of the laundry, when the controller 52determines that laundry is wet cloth, the controller 52 may equalize awet condition of the laundry before determining a weight of the laundryusing the wet cloth weight table.

In order to equalize a wet condition of laundry, a wetting process or avessel cleansing process can be used.

When a wetting process is used to equalize a wet condition of laundry,water is supplied to the tub 11 until the water reaches a wetting level,the washing motor 14 rotates in left and right directions to fully wetthe laundry, and then, the drum 12 rotates to dehydrate the laundry.

Alternatively, the controller 52 may determine a weight of the laundryafter adding a weight to the wet cloth weight table according to achanged amount in water level.

The memory 54 may store control data for controlling operations of thewashing machine 1, reference data that is used to control operations ofthe washing machine 1, operation data that is generated while thewashing machine 1 performs a predetermined operation, settinginformation such as setting data input by the input unit 90 in order forthe washing machine 1 to perform a predetermined operation, the numberof times the washing machine 1 has performed a predetermined operation,and model information of the washing machine 1. When the washing machine1 operates wrongly, the memory 54 may further store fault information,such as information about a cause of the wrong operation and informationabout a location at which the wrong operation has occurred.

The driver 56 may drive the washing motor 14, the drain motor 22, andthe water-supply valve 42 related to an operation of the washing machine1, according to a driving control signal of the controller 52.

The display unit 58 may display an operation state of the washingmachine 1 and a manipulation state of the user, according to a displaycontrol signal of the controller 52.

Hereinafter, a control method of the washing machine 1, according to anembodiment of the present disclosure, will be described with referenceto FIGS. 2 and 3.

FIG. 3 is a flowchart illustrating a control method of a washingmachine, according to an embodiment of the present disclosure. Thecontrol method relates to an algorithm for determining a weight oflaundry in consideration of the result of determination on whether thelaundry is dry cloth or wet cloth.

Referring to FIGS. 2 and 3, if a user selects a wash course (a standardcourse, a wool course, or a delicate course) according to a kind oflaundry, and inputs driving information related to an operation of thewashing machine 1 after the user puts the laundry in the drum 12,information about the selected course and the driving information may betransferred to the controller 52 through the input unit 50. Then, theuser may manipulate one of the operation buttons 51 to input anoperation start command to the washing machine 1.

Then, the controller 52 may determine whether the washing machine 1starts operating (operation 100), and if the controller 52 determinesthat the washing machine 1 starts operating, the controller 52 maymeasure a current level W1 of water loaded in the tub 11 using the waterlevel sensor 19 before starting washing (operation 102).

Then, the controller 52 may store the measured level W1 of water loadedin the tub 11 in the memory 54.

Successively, the controller 52 may drive the washing motor 15 throughthe driver 56 to rotate the drum 12 at first RPM (about 90 RPM to 150RPM for dehydrating water contained in laundry) (operation 104).

The first RPM is RPM at which laundry starts being pushed against theinner wall of the tub 11. The first RPM may be set to any RPM higherthan about 90 RPM. That is, the first RPM may be set to RPM capable ofdehydrating water contained in laundry.

The controller 52 may count a time for which the drum 12 rotates at thefirst RPM, and determine whether a first time period (about 1 to 2minutes for which water contained in laundry can be dehydrated) haselapsed (operation 106).

If the controller 52 determines that the first time period has notelapsed, the controller 52 may return to operation 104 to continue torotate the drum 12 until the first time period has elapsed. If the drum12 continues to rotate in the same direction, the laundry is pushedagainst the drum 12 so that the laundry is dehydrated and water iscollected in the tub 11.

Meanwhile, if the controller 52 determines that the first time periodhas elapsed, the controller 52 may stop operating the washing motor 14through the driver 56, and then measure a level W2 of water collected inthe tub 11 after the drum 12 rotates, using the water level sensor 19(operation 108).

Thereafter, the controller 52 may compare the level W1 of water measuredbefore the drum 12 rotates to the level W2 of water measured after thedrum 12 rotates, and determine whether there is a difference between thelevel W1 of water and the level W2 of water (operation 110).

If the controller 52 determines whether there is a difference betweenthe level W1 of water and the level W2 of water, the controller 52 maydetermine that the laundry put into the drum 12 is wet cloth, anddetermine a weight of the laundry using a wet cloth weight table.

When the controller 52 determines that the laundry is wet cloth, thecontroller 52 may execute a wetting algorithm in order to equalize a wetcondition of the laundry since a level of water measured after the drum12 rotates depends on a wet degree of the laundry.

In order to execute the wetting algorithm, the controller 52 may operatethe water-supply valve 42 through the driver 56 to supply water (washingwater) required for a wetting process.

If the water supply valve 42 operates, the water supply valve 42 opensso that water (wash water) supplied through an external water supplypipe is supplied to the tub 11 through the water supply pipe 40(operation 112).

The controller 52 may measure a level of water supplied to the tub 11through the water level sensor 19, and supply water to the tub 11 untila level of water supplied to the tub 11 reaches a wetting level (a levelof water at which the laundry can be fully wet).

An amount of water that is consumed until a level of water loaded in thetub 11 reaches the wetting level has been given in advance by anexperiment. For example, an amount of water that is consumed until alevel of water loaded in the tub 11 reaches the wetting level when wateris supplied to the tub 11 after laundry is put into the drum 12 can bemeasured. The wetting level may be set to a low level of water such thatlaundry of a predetermined volume can be wetted regardless of an amountof laundry put into the drum 12.

Generally, the washing machine 1 divides water level frequencies thatcan be detected by the water level sensor 19 into a plurality of waterlevel frequency bands, and controls supply of water until a water levelfrequency detected by the water level sensor 19 reaches a goal waterlevel frequency band. Accordingly, the wetting level may be set to avalue corresponding to a minimum level of water among levels of waterwhen water is supplied in correspondence to the water level frequencybands.

If a level of water supplied to the tub 11 reaches the wetting level,the controller 52 may stop operating the water supply valve 42 to stopsupplying water.

Thereafter, the controller 52 may rotate the washing motor 14 in leftand right directions for a second time period (about 1 to 3 minutes forwhich the laundry can be wetted) through the driver 56, therebyperforming a wetting process (operation 114).

In detail, after water is supplied to the drum 12 until a level of waterreaches the wetting level, the pulsator 13 is connected to the washingshaft 17 of the washing motor 14 to drive the washing motor 14 at secondRPM (about 40 RPM to 50 RPM at which the laundry can be wetted), therebyrotating the pulsator 13 in left and right directions.

If the pulsator 13 rotates in the left and right directions by left- andright-directional rotations of the washing motor 14, the laundry loadedin the drum 12 is wetted with water.

The second RPM is RPM at which laundry can be wetted by generating waterstreams for transferring water to the laundry. The second RPM may be setto any RPM higher than about 40 RPM. That is, the second RPM may be setto RPM capable of wetting laundry.

The controller 52 may count a time for which the drum 12 rotates at thesecond RPM, and perform a wetting process for a second time period(about 1 to 3 minutes).

If the wetting process terminates, the controller 52 may determine thatthe laundry has been fully wetted, and perform dehydrating (operation116).

As such, when the controller 52 determines that the laundry put into thedrum 12 is wet cloth, the controller 52 may equalize a wet condition ofthe laundry by performing a series of processes of supplying water anddehydrating by rotating the washing motor 14 in left and rightdirections.

After the controller 52 equalizes the wet condition of the laundry, thecontroller 52 may determine a weight (a load) of the laundry put intothe drum 12 using the wet cloth weight table (operation 118).

Alternatively, the controller 52 may determine a weight (a load) of thelaundry put into the drum 12 after adding a weight to the wet clothweight table according to a changed amount in water level.

The controller 52 may determine a weight of the laundry by calculatingan acceleration time taken for the velocity of the drum 12 to reach apredetermined velocity when applying predetermined torque (or, apredetermined voltage) after accelerating the velocity of the drum 12 toa predetermined velocity. Since the acceleration time is proportional tothe weight of the laundry, the controller 52 may estimate a weight ofthe laundry using a wet cloth weight table corresponding to theacceleration time.

The controller 52 may determine a weight of the laundry using a methodselected from among: a method of determining a weight of laundry byapplying a predetermined duty of about 90V to the washing motor 14 whilerotating the washing motor 14 at predetermined RPM between 70 RPM and150 RPM for detecting a weight of laundry, and calculating a time takenfor the washing motor 14 to reach a predetermined duty and an angularvelocity when the washing motor 14 reaches the predetermined duty; amethod of determining a weight of laundry by calculating a time takenfor the washing motor 14 to reach a predetermined velocity (orpredetermined RPM) using instantaneous acceleration of the washing motor14; and a method of determining a weight of laundry using Newton'ssecond law of motion (torque=the moment of inertia x acceleration) afterdirectly or indirectly measuring a moment of inertia of the drum 12 byapplying torque to the washing motor 14 for a predetermined time period,as disclosed in Japanese Patent Applications Nos. 2002-336593,2004-267334, and 07-90077.

Meanwhile, if the controller 52 determines whether there is nodifference between the level W1 of water and the level W2 of water inoperation 110, the controller 52 may determine that the laundry put intothe wash tub 12 is dry cloth, and the controller 52 may determine aweight of the laundry using a dry cloth weight table (operation 120).

At this time, the controller 52 may determine a weight of the laundryusing the same method of determining a weight of laundry, as describedabove, although using a different weight table corresponding to anacceleration time.

As such, by determining a weight of laundry using different weighttables depending on whether laundry is dry cloth or wet cloth, theweight of the laundry can be accurately determined.

If the weight (load) of the laundry is determined, the controller 52 mayset RPM and a driving rate (on-off times) of the wash water 14, goallevels of water (a goal level of washing water and a goal level ofrinsing water), a washing time, and a rinsing time, according to thedetermined weight (load) of the laundry (operation 122).

Setting goal RPM and a driving rate (on-off times) of the wash water 14,a goal level of washing water, a goal level of rinsing water, a washingtime, and a rinsing time, according to a weight (load) of laundry may beperformed when a user inputs no command regarding an operation of thewashing machine 1. If a user inputs a command regarding an operation ofthe washing machine 1, the goal RPM and the driving rate (on-off times)of the wash water 14, the goal level of washing water, the goal level ofrinsing water, the washing time, and the rinsing time, set according tothe weight (load) of the laundry may be changed according to the commandfrom the user.

Successively, the controller 52 may perform the following processes(specifically, a washing process, a rinsing process, and a dehydratingprocess) of the washing machine 1 using the goal RPM and the drivingrate (on-off times) of the wash water 14, the goal level of washingwater, the goal level of rinsing water, the washing time, and therinsing time, set according to the weight (load) of the laundry(operation 124).

Meanwhile, the above-described embodiment relates to a case in which amethod of determining a weight of laundry in consideration of the resultof determination on whether the laundry is dry cloth or wet cloth isapplied to a full automatic washing machine such as the washing machine1, however, the present disclosure can be applied to a drum washingmachine 301 as illustrated in FIG. 4 so that the same purposes andeffects as in the above-described embodiment can be achieved.

FIG. 4 is a cross-sectional view illustrating a configuration of awashing machine according to another embodiment of the presentdisclosure.

Referring to FIG. 4, a washing machine 1001 may include a main body 1010having a box shape and constituting an external appearance of thewashing machine 1001, a tub 1020 installed inside the main body 1010, adrum 1030 rotatably installed inside the tub 1020, and a motor 1040configured to drive the drum 1030.

In the front part of the main body 1010, an opening 1011 to put laundryinto the drum 1030 may be formed, and the opening 1011 may be opened orclosed by a door 1012 installed on the front part of the main body 1010.

The drum 1030 may include a cylindrical portion 1031, a front plate 1032formed in the front side of the cylindrical portion 1030, and a rearplate 1033 formed in the rear side of the cylindrical part 1030. A hole1032 a for putting laundry into the drum 1030 or taking laundry out ofthe drum 1030 may be formed in the front plate 1032, and a driving shaft1043 for transferring power from a motor 1040 may be connected to therear plate 1033.

A plurality of through-holes 1034 through which wash water passes may beformed around the drum 1030, and a plurality of lifters 1035 may beformed in the inner peripheral surface of the drum 1030 so that laundryrises and falls down when the drum 1030 rotates.

The motor 1040 may include a stator 1041 fixed onto the rear part of thetub 1020, a rotor 1042 rotating while interacting with the stator 1041,and a driving shaft 1043 wherein one end is fixed on the center of therotator 1042, and the other end penetrates the tub 1020 and is fixed onthe center of the rear plate 1033 of the drum 1030.

The driving shaft 1043 may be disposed between the drum 1030 and themotor 1040. One end of the driving shaft 1043 may be connected to therear plate 1033 of the drum 1030, and the other end of the driving shaft1043 may extend out of the rear wall of the tub 1020. If the motor 1040drives the driving shaft 1043, the drum 1030 connected to the drivingshaft 1043 may rotate with respect to the driving shaft 1043.

A bearing housing 1021 to rotatably support the driving shaft 1043 maybe installed in the rear wall of the tub 1020. The bearing housing 1021may be made of an aluminum alloy, and inserted into the rear wall of thetub 1020 when the tub 1020 is injection molded. Bearings 1022 may beinstalled between the bearing housing 1021 and the driving shaft 1043 inorder to smoothly rotate the driving shaft 1043.

The tub 1020 may be supported by a damper 1023. The damper 1023 mayconnect the outer surface of the tub 1020 to the inner, lower surface ofthe main body 1010.

Above the tub 1020, a water supply unit 1050 to supply water to the tub1020, and a detergent supply unit 1070 connected to the water supplyunit 1050 and configured to supply water supplied through the watersupply unit 1050 to the tub 1020 together with a detergent may beprovided. Below the tub 1020, a drain unit 1060 to discharge waterloaded in the tub 1020 out of the main body 1010 may be provided.

The water supply unit 1050 may include water supply pipes 1051connecting an external water supply source (not shown) to the detergentsupply unit 1070 in order to supply water (wash water or rinse water) tothe tub 1020, water-supply valves 1052 installed in the water supplypipes 1051 and configured to control supply of water, and a connectionpipe 1053 connecting the detergent supply unit 1070 to the tub 1020.

The drain unit 1060 may include a drainpipe 1061 to discharge waterloaded in the tub 1020 to the outside, and a drain pump 1062 installedin the drainpipe 1061 and configured to discharge water through thedrainpipe 1061.

The detergent supply unit 1070 may be connected to the tub 1020 throughthe connection pipe 1053 connected to the lower part of the detergentsupply unit 1070. Water supplied through the water supply pipes 1051 maypass through the detergent supply unit 1070 and be supplied to the tub1020 through the connection pipe 1053. This structure is aiming atcausing water to be supplied to the tub 1020 via the detergent supplyunit 1070 so that a detergent contained in the detergent supply unit1070 can be supplied to the tub 1020 together with water. The washingmachine 1001 may also include sensors 1080, 1082 and 1084.

According to the washing machine and the control method thereof asdescribed above, before washing starts, the drum rotates to measure achanged amount in water level, and it is determined whether laundry isdry cloth or wet cloth based on the changed amount in water level. Ifthe laundry is wet cloth, a weight of the laundry is accurately detectedby using weight criteria corresponding to wet cloth, which leads toreducing water consumption, a washing time, and energy consumption whilepreventing laundry from being damaged.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A control method of a washing machine, thewashing machine including a tub to accommodate water therein, and a drumrotatably installed in the tub and configured to accommodate laundrytherein, the control method comprising: determining whether the washingmachine starts operating; rotating, if it is determined that the washingmachine starts operating, the drum before supplying water to the tub;measuring a changed amount in water level according to the rotation ofthe drum to determine whether the laundry is dry cloth or wet cloth; andsetting, if it is determined that the laundry is wet cloth, a washingcondition corresponding to wet cloth.
 2. The control method according toclaim 1, further comprising a washing motor configured to rotate thedrum, wherein the rotating of the drum comprises rotating the washingmotor at Revolution Per Minute (RPM) for dehydrating water contained inthe laundry.
 3. The control method according to claim 2, wherein the RPMis equal to or more than 90 RPM.
 4. The control method according toclaim 1, further comprising a water level sensor configured to measure alevel of water loaded in the tub, wherein the determining of whether thelaundry is dry cloth or wet cloth comprises: measuring a level of waterloaded in the tub using the water level sensor before rotating the drum;measuring a level of water loaded in the tub using the water levelsensor after rotating the drum; and measuring a changed amount in waterlevel by comparing the level of water measured before rotating the drumto the level of water measured after rotating the drum to determinewhether the laundry is dry cloth or wet cloth.
 5. The control methodaccording to claim 4, further comprising determining, if a changedamount in water level is measured, that the laundry is wet cloth.
 6. Thecontrol method according to claim 4, further comprising determining, ifno changed amount in water level is measured, that the laundry is drycloth.
 7. The control method according to claim 1, wherein the settingof the washing condition corresponding to wet cloth comprisesdetermining a weight of the laundry using weight criteria that isdifferent from weight criteria to be used when the laundry is dry cloth.8. The control method according to claim 7, wherein the washing machinefurther includes a washing motor configured to rotate the drum, andwherein the determining of the weight of the laundry comprisesestimating a weight of the laundry using an acceleration time taken forthe drum to reach a predetermined velocity when predetermined torque isapplied to the washing motor.
 9. The control method according to claim7, wherein the determining of the weight of the laundry comprisesperforming, if it is determined that the laundry is wet cloth, a wettingprocess to wet the laundry, and then estimating a weight of the laundry.10. The control method according to claim 4, wherein the determining ofwhether the laundry is dry cloth or wet cloth is performed before awater supply process of initially supplying water in order to wash thelaundry.
 11. The control method according to claim 4, wherein thedetermining of whether the laundry is dry cloth or wet cloth isperformed before determining the weight of the laundry.
 12. A washingmachine comprising: a tub configured to accommodate water therein; adrum rotatably installed in the tub and configured to accommodatelaundry therein; a washing motor configured to rotate the drum; and acontroller configured to control the washing motor to rotate the drumbefore supplying water to the tub, to measure a changed amount in waterlevel according to the rotation of the drum, and to set a washingcondition according to the changed amount in water level.
 13. Thewashing machine according to claim 12, wherein the controller rotatesthe drum at Revolution Per Minute (RPM) for dehydrating water containedin the laundry.
 14. The washing machine according to claim 12, furthercomprising a water level sensor configured to measure a level of waterloaded in the tub, wherein the controller measures a level of waterloaded in the tub using the water level sensor before rotating the drum,measures a level of water loaded in the tub using the water level sensorafter rotating the drum, and measures a changed amount in water level bycomparing the level of water measured before rotating the drum to thelevel of water measured after rotating the drum to determine whether thelaundry is dry cloth or wet cloth.
 15. The washing machine according toclaim 14, wherein if a changed amount in water level is measured, thecontroller determines that the laundry is wet cloth.
 16. The washingmachine according to claim 12, wherein the controller determines aweight of the laundry using an acceleration time taken for the washingmotor to reach a predetermined velocity when predetermined torque isapplied to the washing motor.
 17. The washing machine according to claim16, wherein if it is determined that the laundry is wet cloth, thecontroller performs a wetting process to wet the laundry beforedetermining a weight of the laundry.
 18. The washing machine accordingto claim 12, wherein the controller determines whether the laundry isdry cloth or wet cloth according to the changed amount in water level,and determines a weight of the laundry using different weight criteriondepending on whether the laundry is dry cloth or wet cloth.
 19. Thewashing machine according to claim 16, further comprising a memoryhaving a wet cloth table and a dry cloth table, wherein the controllerestimates the weight of the laundry using the wet cloth table or the drycloth table corresponding to the acceleration time.
 20. The washingmachine according to claim 19, wherein, when the controller utilizes thewet cloth table, the controller estimates the weight of the laundryusing the wet cloth table after a adding a weight to the wet cloth tableaccording to the changed amount in water level.